A lighting or indicator device of this kind usually comprises a lamp which is fitted inside a casing which may act as a reflector, through an opening in the rear of the reflector and which is locked into the lamp holder.
One of the arrangements currently used for locking and unlocking the lamp consists of a circular collar on the lamp holder against which is applied a circular flange of the lamp, and securing the lamp by means of a spring element made of steel wire. Means of articulating the spring element are provided on the lamp holder, and means for hooking on and for releasing the said spring element are provided in a region of the lamp holder substantially diametrically opposite the articulating means.
The ends of the steel wire constituting the spring element are disposed in the locking and unlocking means in such a way that its release is effected by squeezing the ends in a direction perpendicular to the axis of insertion of the lamp in the reflector. Such means are effective and of simple design, and are described, for example, in French patent Nos. FR 1 313 934 and FR 2 036 783 (GB No. 1256485).
Nevertheless, such a device has the disadvantage of requiring a large working space behind the lamp because the ends of the steel wire constituting the spring element are off-set relative to the axis of insertion of the lamp and must be compressed by hand or by a tool to lock or unlock the lamp.
Moreover, in some cases, such a design enables the spring element to drop down under its own weight against the locking and unlocking means, which may mislead the user into believing that the lamp is secured.
An object of the present invention is to overcome these disadvantages by proposing a simple, effective system for releasably locking a lamp in a lamp holder, requiring only a minimum space for manipulation.